1. Field of the Invention
The present invention relates to an image forming apparatus, such as a printer and a copier, having a function of discharging a gas generated within the apparatus to the outside thereof.
2. Description of the Related Art
Some image forming apparatuses are provided with an exhaust fan, an exhaust duct, and a filter to reduce or remove an odorous substance volatilized from toner due to the heat generated in a fixing process and/or to reduce or remove ozone generated from a charging unit.
Thus, for example, an activated carbon filter is arranged between the front and rear sides in the ventilation direction to reduce pressure loss in the exhaust duct and provide a beneficial deodorizing effect.
Along with improvement of office environment, odor, for example, has become more noticeable than before, and the reduction thereof has been required. The odorous substance removal efficiency can be increased by providing plural types of filters or filtering capacities. However, the pressure loss in a filter unit is increased in accordance with the number of provided filters. The increase in pressure loss leads to an increase in output of the exhaust fan, and therefore causes an increase in noise and power consumption due to an increase in rotation rate of the fan.
According to the above-described background example, the activated carbon filter is arranged between the front and rear sides in the ventilation direction. That is, the filter is arranged perpendicular to the airflow in the exhaust duct. Thus, the configuration is open to improvement in terms of pressure loss. Further, as with another background example illustrated in FIG. 1, if the filter is arranged perpendicular to the ventilation direction of the exhaust duct, the influence of fan wind (i.e., dynamic pressure) generated by the exhaust fan on the air passing through the filter is relatively large, and the wind velocity of the airflow passing through the filter tends to vary due to uneven impact of the wind on the filter. Further still, the generation of odor varies depending on the way the image forming apparatus is used, and moreover the perception of odor is substantially different from person to person.